Subsurface pump and drive



June 9, 1964 R. 1 CHENAULT 3,136,256

SUBSURFACE PUMP AND DRIVE Filed oct. 12, 1962 Allorney United StatesPatent O 3,136,256 SUBSUEFACE PUMP ANB DRIVE Roy I.. Chenault, llallas,Tex., assigner to United States Steel Corporation, a corporation of NewIersey Filed Oct. 12, 1962, Ser. No. 236,188 9 Claims. (Cl. 1633-46)This invention relates to improved subsurface pumps for handling oilswhich have volatile constituents.

Oil in some wells has a high content of readily volatile constituents,such as propane or butane. When these constituents boil within a well,they may cause a vapor lock in a subsurface pump. The pump cannot bringoil to the surface, and the well appears to have pumped off. Forexample, the vapor pressure of propane at 110 F. is about 213 p.s.i. Inmany Wells the fluid column has a density such that about 3 feet oflluid head represents one pound per square inch of pressure. Under theseconditions a fluid column of about 630 feet is required to preventpropane from boiling at the bottom. Thus a well may appear to pump offwhen it has up to 630 feet of fluid remaining above the pump inlet. n

An object of the present invention is to provide improved subsurfacepumps whch automatically allow vapors to escape, thereby enabling thepump to raise oil to the surface despite a high content of volatileconstituents.

A further object is to provide improved subsurface I pumps whichautomatically vent thebarrel to the casing near the end of each intakestroke, allowing oil to replace vapors.

A further object is to provide improved subsurface pumps whichautomatically equalize the pressure inside and outside the pump barrelat the end of each intake stroke, thereby assuring that the pump picksup a representative sample of well fluid.

In accomplishing these and other objects of the invention, I haveprovided improved details of structure, preferred forms of which areshown in the accompanying drawing, in which:

FIGURE l is a diagrammatic vertical section of a casing-type subsurfacepump constructed in accordance with my invention;

FIGURE 2 is a diagrammatic vertical sectionof surface equipment which Ican use for actuating the pump shown in FIGURE 1; and

FIGURE 3 is a diagrammatic vertical section of a tubing-type subsurfacepump constructed in accordance with myv invention.

FIGURE 1 shows the lower portionV of an oil well which contains aconventional casing 10. The pump of my invention includes an elongatedtubular barrel 12 and conventional slips 13 or equivalentV which anchorthe barrel in the casing. The barrel contains a vertically movablereciprocable hollow plunger 14, therupper end of which is attached to atubular rod string 15. The lower end of the barrel has an intake opening16 and the side walls have vent ports 17 located intermediate the lengthof the barrel. A standing valve 18 is mounted at the lower end of thebarrel over the intake opening 16. The lower end of the plunger hasports 19. A traveling valve 20 is mounted at the lower end of theplunger over the last-named ports. I mount the standing valve 1S in acage 21. A rod 22 is attached to the top of cage 21 and extends upwardlytherefrom through openings in the bottom of plunger 14 and travelingvalve 20 into the interior of the hollow plunger. The upper end of rod22 carries a'knob or shoulder 23. The upper end of the pump barrel has ashoulder 24 to limit upward travel of the plunger.

In operation, a drive mechanism at the surface alternately raises andlowers the tubular rod string 15 and plunger 14. Preferably the drive isof a type which produces a long stroke on the order of 20 to 30 feet andis equipped with a timer which automatically stops the rod string forseveral seconds at the end of each intake stroke. One example of asuitable drive is described hereinafter. During an upstroke oftheplunger, the standing valve 1S opens and the traveling valve 20 closes.The plunger draws well fluid into barrel 12 through the intake opening16 in the usual way. The plunger covers'the Vent ports 17 until itapproaches the top of its upstroke. When the plunger moves past theseports and uncovers them, the interior of the barrel is vented to thecasing. Continued upward movement of the plunger lifts rod 22 and cage21 to hold the standing valve open. Thus gas which accompanies oil inthe well, along with vapors which form as volatile constituents boil,escape into the casing. The pause in movement of the plunger allowssuicient time. During a downstroke the standing valve closes and thetraveling valve opens. Well fluid is forced from the pump barrel throughports 19 into the plunger, and up the bore of the tubular rod string 15to the surface.

FIGURE 2 shows one form of mechanism I can use for delivering well uidat the surface from the pump shown in FIGURE 1 and also actuating thepump. A cylindrical chamber 28 is xed within the upper end of the casing10. The tubular portion 15 of the rod string terminates lwithin chamber28 and has discharge ports 29 therein. A polished rod 30 is attached tothe upper end of the rod string 15. Chamber 28 has stuffing boxes 31 and32 at opposite ends through which the tubular rod string and thepolished rod extend. A single-acting drive cylinder 33 is positionedabove the top of tubing 10. A piston 34 is attached to the upper end ofthe polished rod and housed in cylinder 33. The lower portion of thecylinder has a connection 35 for admitting and discharging hydraulicfluid. This connection leads to a motivating pump and valve (not shown).Cylinder 33 has spaced upper and lower pressure taps 36 and 37 foractuating timing and reversing mechanism (not shown). Reference can bemade to my earlier Patent No. 2,665,551 for a showing of a motivatingpump and associated mechanisms suitable for this purpose. The circuitwhich energizes the motivating pump can be equipped with a conventionaltimer for producing a pause in movement of the rod string at the end ofeach intake stroke.L Chamber 28 has a discharge opening 38, and thecasing 1li a vent opening 39.

In operation, hydraulic fluid is forced into the drive cylinder 33through the connection 35 to raise piston 34 and thus produce anupstroke of the rod string 15 and pump plunger 14. In the embodiment ofmy pump shown in FIGURE 1, the upstroke is the intake stroke; hence theforce required is only that needed to lift the rod string. During thedownstroke the rod string moves by gravity. The weight of the rods thusfurnishes the force needed to deliver well fluid to the surface. In thismanner I avoid the need to counterbalance the weight of the rods,although of course I can use a counterbalance as shown in myaforementioned patent to diminish still further the force required foran upstroke.

FIGURE 3 shows a modification in which I apply my venting principles toa tubing-type pump. The ligure shows the lower portion of an oil wellwhich contains a conventional casing i2 and tubing 43. An elongatedtubular barrel ld is fixed to the lower end of the tubing and has alower head 45 which contains intake openings 46. The barrel contains areciprocable plunger 47, the upper end of which is attached to afinished tube 48. I connect the upper end of tube 43 to a rod string 49,the lower end or which has spaced shoulders 5G and 51 to provide alost-motion connection between the rod string aieaaee and the plunger. Imount vertically spaced upper and lower liners 52 and 53 within barrel44. These liners closely receive the outside of tube 4S and they dividethe interior of the pump barrel into chambers 54 and 55. The plunger 47contains an intake valve 56, and tube 43 a check valve 57. Tube 4S hasports 53 and 59 near its lower and upper ends respectively, and a seriesof vertical grooves 6i? in its outer surface intermediate its length.The barrel 44 has vent ports 6l' which afford communications betweenchamber 55l and casing 42. The lower head 45has an upstanding stern 62for holding the intake valve 56 open at the bottom of a downstroke.

In operation, a drive mechanism (not shown) at the surface alternatelyraises and lowers the rod string 49. The drive can be similar to thatalready described, except that preferably it is equipped with acounterbalance, since in this instance the upstroke is the deliverystroke. During a downstroke the intake valve 56 opens, while the weightof the fluid column in the tubing holds valve 57 closed. Well fiuidenters the chamber 54 within the pump barrel through openings 46, theopen valve S6, and ports 58. The close fit of the finished tube 48 inliner 53 blocks liow of fluid from chamber 54 to chamber 55 until theplunger approaches the end of its downstroke. When the finished tubereaches a position near the end of the downstroke, grooves 6) establishcommunication between chambers 54 and 55, whereby chamber S4 is ventedto the casing. On continued downward movement of the plunger, stem 62holds the intake valve 60 open. Thus gas which accompanies oil in thewell, along with vapors which form as volatile constituents boil, escapeinto the casing. The pause in movement of the plunger allows sufficienttime. During the upstroke the intake valve 56 closes and the check valve57 opens. Well fluid is forced from chamber 54 through ports 58, theopen valve 57 and ports 59 into the tubing 43 and thence to the surface.

From the foregoing description, it is seen that either embodiment of mysubsurface pump allows free circulation of well fluid through the intakeopening 16 or 46 and out the vent ports 17 or 61 during the pause at theend of an intake stroke. Consequently the pump picks up a representativesample of fluid under conditions identical with those in the welloutside the barrel. Even though a liquid is boiling violently, thevolume of vapor is relatively'small. Hence I obtain a high volumetricefficiency by admitting a truly representative sample of well fluid tothe barrel. However, even a slight pressure drop in a boiling liquidcauses a fiashing into vapor which may completely fill the pump barrelon the intake stroke and recondense with only a small pressure increaseon the delivery stroke to form an insignificant volume of liquid. Botharrangements I have shown avoid this vapor lock condition by assuringthat the pressure inside the pump barrel is exactly the same as thatoutside.

While I have shown and described certain preferred embodiments of myinvention, it is apparent that other modifications may arise. Therefore,I do not wish to be limited to the disclosure set forth but only by thescope of the appended claims.

I claim:

1. A subsurface pump comprising an elongated tubular barrel, avertically movable reciprocable element housed within said barrel andadapted to make intake and delivery strokes as it travels in oppositedirections, a first valve which closes during a delivery stroke butopens during an intake stroke to admit fiuid to said barrel, a secondvalve which closes during an intake stroke but opens during a deliverystroke to enable said element to force fluid from said barrel, saidbarrel having a vent port intermediate its length, said element reachinga position near the end of its intake stroke in which said port affordscommunication between the interior of said barrel and the exterior butotherwise closing said port, and means for holding said first valve openwhen said element reaches the end of its intake stroke to allowvolatiles t0 escape from said barrel through said port and liquid toenter the barrel through said first valve to replace escaped volatiles.

2. A pump as defined in claim 1 in which said element travels upwardlyas it makes its intake stroke and downwardly as it makes its deliverystroke, said first valve is a standing valve mounted in said barrelbelow said element, and said second valve is a traveling valve mountedin said element.

3. A pump as defined in claim 2 in which the means for holding saidfirst valve open includes a cage in which said first valve is mounted, arod extending upwardly from said cage and into said element, and a knobon the upper end of said rod for lifting said cage.

4. A pump as defined in claim 1 in which said element travels downwardlyas it makes its intake stroke and upwardly as it makes its deliverystroke, said first valve is an intake valve mounted in said element nearthe lower end thereof, and said second valve is a check valve mounted insaid element above said first valve.

5. A pump as defined in claim 4 in which the means for holdin'T saidfirst valve open includes an upstanding stem fixed to the lower end ofsaid barrel.

6. A subsurface pump comprising an elongated tubular barrel, avertically movable hollow reciprocable plunger housed within said barreland adapted to make an intake stroke as it travels upwardly and adelivery stroke as it travels downwardly, a standing valve which ismounted in said barrel below said plunger and closes during a deliverystroke but opens during an intake stroke to enable said plunger to drawfiuid into said barrel, a traveling valve which is mounted in saidplunger and closes during an intake stroke but opens during a deliverystroke to enable said plunger to force fluid from said barrel, saidbarrel having a vent port intermediate its length, said plunger reachinga position near the end of its intake stroke in which said port isuncovered and affords communication between the interior of said barreland the exterior but otherwise covering said port and preventingcommunication therebetween, and means connecting said plunger and saidstanding valve for holding said standing valve open when said plungerreaches the end of its intake stroke to allow volatiles to escape fromsaid barrel through said port and liquid to enter the barrel throughsaid first valve to replace escaped volatiles.

7. A casing-type subsurface pump comprising an elongated tubular barrel,means for anchoring said barrel in a casing, a vertically movablereciprocable hollow plunger housed within said barrel and adapted tomake an intake stroke as it travels upwardly and a delivery stroke as ittravels downwardly, a tubular rod string connected to said plunger fordriving it up and down, a standing valve which is mounted in said barrelbelow said plunger and closes during a delivery stroke but opens duringan intake stroke to enable said plunger to draw fluid into said barrel,a traveling valve which is mounted in said plunger and closes during anintake stroke but opens during a delivery stroke to enable said plungerto force fluid from said barrel into said rod string, said barrel havinga vent port intermediate its length, said plunger reaching a positionnear the end of its intake stroke in which said port 1s uncovered andaffords communication between the interior of said barrel and theexterior but otherwise covering said port and preventing communicatlon.therebetween, and means connecting said plunger and said standing valvefor holding said standing valve open when said plunger reaches the endof its intake stroke to allow volatiles to escape from said barrelthrough said port and liquid to enter the barrel through said firstvalve to replace escaped volatiles.

8. A subsurface pump comprising an elongated tubular barrel, avertically movable reciprocable plunger housed within said barrel andadapted to make an intake stroke as it travels downwardly and a deliverystroke as it travels upwardly, a finished tube fixed to said plunger andextending upwardly therefrom, vertically spaced upper and lower linersfixed within said barrel and closely receiving said tube, said linersdividing the interior of said barrel into a iirst chamber below saidlower liner and a second chamber between the two liners, said tubehaving ports which afford communication between the interior of the tubeand said iirst chamber, an intake valve which is mounted in said plungernear the lower end thereof and closes during a delivery stroke but opensduring an intake stroke to admit iiuid to said tube and through saidports into said first chamber, a check valve which is mounted in saidtube and closes during an intake stroke but opens during a deliverystroke to enable said plunger to force fluid from said iirst chamberthrough said tube, said barrel having a vent port leading to said secondchamber, said tube having external grooves along a portion of itslength, said tube reaching a position near the end of an intake strokein which said grooves afford communication between said irst and secondchambers but otherwise preventing such communication, and means on saidbarrel for holding said intake valve open when said plunger reaches theend of its intake stroke to allow volatiles to escape through said ventport and liquid to enter the barrel through said intake valve to replaceescaped volatiles.

9. A tubing-type subsurface pump comprising an elongated tubular barrel,a vertically movable reciprocable plunger housed Within said barrel andadapted to make an intake stroke as it travels downwardly and a deliverystroke as it travels upwardly, a finished tube fixed to said plunger andextending upwardly therefrom, vertically spaced upper and lower linerslixed Within said barrel and closely receiving said tube, said linersdividing the interior of said barrel into a first chamber below saidlower liner and a second chamber between the two liners, said tubehaving ports which atord communication between the interior of the tubeand said first chamber and other ports which afford communicationbetween the interior of the tube and barrel above said upper liner, anintake Valve which is mounted in said vplunger near the lower endthereof and closes during a delivery stroke but opens during an intakestroke to admit iiuid to said tube and through said rst-named ports intosaid lirst chamber, a check valve which is mounted in said tube andcloses during an intake stroke but opens during a deiivery stroke toenable said plunger to force iuid from said first chamber into said tubeand through said second-named ports, a rod string connected to the upperend ot said tube and having a lost-motion connection therewith, saidbarrel having a vent port leading to said second chamber, said tubehaving external grooves along a portion of its length, said tubereaching a position near the end of an intake stroke in which saidgrooves afford communication between said iirst and second chambers butotherwise preventing such communication, and means on said barrel forholding said intake valve open when said plunger reaches the end of itsintake stroke to allow volatiles to escape through said vent port andliquid to enter the barrel through said intake valve to replace escapedvolatiles.

References Cited in the tile of this patent UNITED STATES PATENTS 53,117Cornelius Mar. 13, 1866 1,659,642 Sorey Feb. 21, 1921 2,171,410 SteeleAug. 29, 1939 2,665,551 Chenault Jan. 12, 1954

1. A SUBSURFACE PUMP COMPRISING AN ELONGATED TUBULAR BARREL, A VERTICALLY MOVABLE RECIPROCABLE ELEMENT HOUSED WITHIN SAID BARREL AND ADAPTED TO MAKE INTAKE AND DELIVERY STROKES AS IT TRAVELS IN OPPOSITE DIRECTIONS, A FIRST VALVE WHICH CLOSES DURING A DELIVERY STROKE BUT OPENS DURING AN INTAKE STROKE TO ADMIT FLUID TO SAID BARREL, A SECOND VALVE WHICH CLOSES DURING AN INTAKE STROKE BUT OPENS DURING A DELIVERY STROKE TO ENABLE SAID ELEMENT TO FORCE FLUID FROM SAID BARREL, SAID BARREL HAVING A VENT PORT INTERMEDIATE ITS LENGTH, SAID ELEMENT REACHING A POSITION NEAR THE END OF ITS INTAKE STROKE IN WHICH SAID PORT AFFORDS COMMUNICATION BETWEEN THE INTERIOR OF SAID BARREL AND THE EXTERIOR BUT OTHERWISE CLOSING SAID PORT, AND MEANS FOR HOLDING SAID FIRST VALVE OPEN WHEN SAID ELEMENT REACHES THE END OF ITS INTAKE STROKE TO ALLOW VOLATILES TO 